Mattresses, sofas or other bedding or seating furniture may be provided with innerspring units. A machine may be provided to form an innerspring unit or a part of an innerspring unit, e.g. a string of pocket springs. Innerspring units which use such pocket springs are generally considered to offer enhanced comfort compared to many conventionally sprung mattresses or other bedding or seating furniture using springs connected by a wire framework.
Machines used for manufacturing an innerspring unit or a portion thereof, such as a string of pocket springs, may have various processing stations. A spring coiler station may be provided to form springs. A pocketing station may be provided to form a string of pocket springs from a plurality of springs and a band of pocket material. The pocketing station may be configured to insert springs into a tube of pocket material and to define the pockets by performing an ultrasonic welding operation, for example.
It is desired that springs can be transported automatically in machines used for forming at least a portion of an innerspring unit. Transport devices of various types may be used for transporting springs in such machines including, without limitation, conveyors, pivot arms, or linearly moving transport elements.
An increasing demand for high operation speed, e.g. a desire to increase the number of springs that can be transported per time, increases the need for securely retaining a spring while it is being transported. Transport devices may be configured to rely on frictional locking, e.g. by providing a clamping force that acts on a compressed spring. When relying only on frictional locking for securing a spring during transport, this may limit the locations at which the transport device may be used and/or may require complex mechanisms for compressing the springs upon insertion into the transport device.